1. Field
The present disclosure relates generally to circuits, and more specifically to techniques for conserving battery power for an electronics device.
2. Background
Wireless devices (e.g., cellular phones) are widely used for various applications such as wireless communication, messaging, video, gaming, and so on. The applications and functions for wireless devices are continually expanding to meet growing consumer demands. Consequently, more sophisticated wireless devices are continually being designed with higher level of integration and faster operating speed in order to support more applications and functions with small device sizes.
Highly integrated wireless devices may consume more power. This may be especially true when operating at a high clock. Higher power consumption can shorten battery life, which is highly undesirable since long battery life is an important design and marketing parameter for portable wireless devices. Hence, a great deal of design effort is often devoted to extending battery life while achieving good performance. For example, wireless devices are often designed to power down as much circuitry as possible when operating in an idle mode to conserve power. An effective method for reducing power consumption when operating in an active mode is to scale or adjust the supply voltage since power consumption is approximately a quadratic function of supply voltage. For example, reducing the supply voltage by 10 percent may save power consumption by almost 20 percent.
The goal of supply voltage scaling is to reduce the supply voltage as much as possible while maintaining the required performance. This may be achieved by identifying a critical signal path in an integrated circuit (IC), e.g., the signal path with the longest delay, and adjusting the supply voltage such that the critical signal path meets timing requirements. This criterion is difficult to establish in modem VLSI circuits for several reasons. First, the critical signal path can change as the supply voltage is varied. One signal path may be critical at one supply voltage while another signal path may be critical at another supply voltage. Second, at a given supply voltage, the critical signal path may vary from die to die based on IC process and temperature variations. Conventionally, these variations are accounted for by adding a large safety margin to ensure proper operation in all conditions. This large safety margin typically results in higher power consumption much of the time.
There is therefore a need in the art for techniques to more effectively conserve battery power for a wireless device.